A Marine and Freshwater Biomedical Sciences Specialized Center of Research is proposed which will utilize components of the administration, facilities, and scientific staff of the Mt. Desert Island Biological Laboratory. The MFBS SCOR will provide the administrative and technical assistance, experimental animals, supplies, and capital equipment to promote the interaction, collaboration, and training of biomedical scientists (both clinicians and physiologists) investigating the toxic effects of heavy metals on membrane function. In addition, it will provide for the rapid dissemination of data derived from these studies. Animal systems will be used which model both passive and active membrane transport processes found in the human renal, intestinal and hepatic epithelia--tissues with known sensitivity to heavy metal toxicity. Specifically, research groups will examine the effects of heavy metals on: 1. Transport of ammonia, H, and HCO3 across the fish gill; 2. Transport of K by the fish urinary bladder; 3. Transport of glucose and amino acids across flounder renal microvesicles, and cotransport of NaCl/KC1 across shark rectal gland microvesicles; 4. Transport of NaCl/KC1 across isolated rectal gland tubules; 5. Maintenance of intracellular pH, Ca concentration, and membrane PD in isolated rectal gland cells; 6. Cellular work of isolated, perfused, and in vitro rectal gland; 7. Transport of amino acids across the fish gut; 8. Volume regulation by rectal gland cells; 9. Stimulus/response coupling of hormonal stimulation of transport of Cl, and vasoactivity, of fish gills; 10. Transport pathways for Na, K and Cl across the fish urinary bladder; 11. Glomerular permeability of the hagfish kidney; 12. Transport of Na and Cl across the fish gill; 13. Transport of Na and Cl across the fish cornea; as well as, 14. The mode of transport of methlymercury across the hepatic duct epithelium. It is proposed that this MFBS SCOR will provide a unique milieu for research and training of present and future biomedical scientists interested in the cellular and sub-cellular mechanisms of the toxic effects of heavy metals.